Raman, infrared, and microwave spectra and conformational preferences of meso-Bisoxirane

Vibrational infrared and Raman spectra of liquid and solid meso-bisoxirane and infrared spectra of the gaseous phase were recorded. Additionally, microwave rotational spectra from 40 to 18 GHz were recorded. The vibrational spectra demonstrate the presence of two conformations in the fluid phases but only one in the solid state. Infrared and Raman activities and gasphase band contours indicate that the trans conformer with C-i molecular symmetry is more stable than the gauche conformer (C-1 symmetry). Variable temperature studies of two pairs of Raman lines are consistent with a Delta H value of 0.31 +/- 0.10 kcal/mol in the liquid state, Rotational constants (A = 9187.45 +/- 0.04, B = 2651.80 +/- 0.01, C = 2608.92 +/- 0.01 MHz) and the dipole moment (mu(total) = 3.03 D) were determined for the gauche conformer. Model calculations give an acceptable match to the observed rotational constants for an H-C-C'-H' dihedral angle of 60 degrees. The relationship of meso-bisoxirane to other similar three-membered ring compounds is discussed. Published by Elsevier Science B.V.